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BIG PHYSICS, BIG QUESTIONS –

Fungus threat to Brazil’s 300 million cocoa trees

By
BRIAN HOMEWOOD in
SAO PAULO

Cocoa growers in Brazil could lose half their crop in the next few years
to a fungus which kills the branches of the trees.

No one knows how the disease reached Bahia, nearly 4000 kilometres from
the Amazon. Producers say it was introduced deliberately by left-wing activists
campaigning for land reform by tying infected branches to healthy trees.

However, investigations by local police have so far proved fruitless.
And others are saying that the spores of the disease were introduced accidentally,
possibly by migrant workers.

Local growers say witches’ broom disease – so called because it leaves
dead branches looking like a broom – has existed in the Amazon for centuries.
Farmers in Bahia, Brazil’s main cocoa growing area, successfully kept the
disease out until around two years ago when the first cases were reported.

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Now the disease has spread across almost all the cocoa zone. Latest
figures from the government cocoa institute, Ceplac, show that several hundred
thousand trees are infected. Brazil has around 300 million cocoa trees.

‘Almost all the cocoa zone has been affected,’ said Ricardo Sgrillo,
research director at Ceplac. ‘The situation is extremely serious. Last November
we were finding 100 trees a day affected by witches’ broom. Now we are finding
1000 a day.’ The only way to get rid of witches’ broom is to prune and
burn the affected branches, leaving the rest of the tree to recover. Ceplac
admits that its initial strategy – razing infected plantations to the ground
– was wrong and discouraged farmers from reporting new outbreaks.

Bahia’s farmers, who have suffered for years because of low prices for
cocoa, cannot afford even to cut branches. ‘It’s not difficult to stop,
but you have to employ two, three or four people just to chop off the branches
and nobody has any money,’ said one producer.

Ceplac is carrying out research into fungicides and is looking for trees
that are resistant to the fungus.